The present invention relates generally to conductive polymers. Specifically, the present invention provides a polymer-latex composite comprising an organic polymeric material dispersed in a latex which is doped to provide an electroconductive polymer-latex composite. The latex effectively serves as a carrier for the polymeric material.
Conductive polymers are well known in the art. They have found uses in making moldable semiconductors and active elements for electronic devices, for example, active elements in electrophotographic copying machines.
Conductive polymers are generally prepared from backbone polymers, such as polyacetylene, which are made electrically conductive by molecular doping of the polymer. Effective doping agents are generally strong reducing or oxidizing agents. Common dopants used include p-tetracyanoquinodimethane (TCNQ), arsenic pentafluoride, and iodine. By doping polymers with these dopants, nominally semiconducting or insulating materials can be made into semiconducting and metallic-like materials. Such materials provide the advantages of the low cost, light weight, moldability and flexibility of polymers along with the desirable properties of electrical conductors.
Although films of electroconductive polymers provide these advantages, they suffer from several disadvantages in certain physical properties. For example, films of polyacetylene are very thin and often brittle. Consequently, they often flake and crumble making them unsuitable for many applications. It has also been observed that films of polyacetylene, after doping, are very sensitive to air and become non-conductive after only a few days. This is believed to be caused by oxidation of the activated polymer.
What is desired is a conductive polymer that retains its electrical properties for a longer period of time when exposed to air. In addition, it is desired to have a conductive polymer which is less brittle and therefore much more easily fabricated into a variety of film shapes.